This invention relates generally to a trailer for marine vehicles adapted to be conveyed by a towing vehicle, and more specifically to an extendable trailer for such vehicles.
Extendable boat trailers of the type including a boat-supporting carriage movable on a wheeled trailer frame or chassis are known in the prior art, as evidenced by U.S. Pat. Nos. 3,138,271 (De Lay et al.); 3,140,003 (Horner); 3,826,391 (Prince); 4,050,595 (Bussard) and 4,365,923 (Lubbers).
The trailer disclosed in the De Lay et al. patent includes a boat-supporting platform which is designed to be slid relative to the chassis of the trailer. A review of this patent shows that it does not overcome one of the primary problems associated with the use of conventional trailers; namely, maintaining the wheels of the trailer out of the water to thereby avoid the corrosive effects of the water on the trailer. In the De Lay et al. construction a movable link member 184 is employed to assist in preventing separation of the platform from the chassis, after the platform has been fully extended.
The Bussard patent (U.S. Pat. No. 4,050,595) discloses an extendable trailer employing a primary winch 24 and an additional winch 40. The winch 40 is employed to positively extend a movable trailer accessory 30 outwardly, by rotation in one direction, and inwardly, by rotation in an opposite direction. To achieve this mode of operation opposite ends of a winch cable associated with the drum 40 are attached at 45 and 47 to a strut 46 of the trailer accessory 30. The primary winch 24 is employed to lock the boat 22 to the trailer bed through a winch cable 28 and connecting bolt 29.
The patent to Lubbers (U.S. Pat. No. 4,365,923) discloses a combination trailer/launcher for boats or other marine vehicles. This trailer employes an inner structure 27 which is movable rearwardly to launch the boat, and this inner structure includes front guide bars and rear guide bars that assume predetermined separate inclinations for launching the boat. This trailer, like the Bussard trailer discussed earlier, employs two winch assemblies 15 and 39 in its construction.
The Prince patent (U.S. Pat. No. 3,826,391) discloses a trailer having a plurality of winches in combination with suitable clutch mechanisms for effecting the desired movement of the members of the trailer. One of the winches is employed to tilt the main frame 21 relative to the ground. A second winch is employed, after the main frame has been tilted, to cause a boat support frame 50 to be telescopically extended rearwardly from the main frame. A third winch is employed to draw the support frame back onto the main frame.
The Horner patent (U.S. Pat. No. 3,140,003) discloses a telescopic boat trailer which employs a pair of winches in its operation. One winch 132 is employed to retract and extend an intermediate telescopic member 56, while the other winch is employed to draw the retracted telescopic frame down into the plane of the tow member 30. Thus, the Horner construction, like some of the earlier described trailers, employs a plurality of winches in its construction and operation.
A number of other patents disclose extendable boat trailers in which the boat supporting carriage of the trailer includes ground-engaging wheels, and is movable relative to other trailer elements to effect the boat launching operation. This type of arrangement is disclosed in U.S. Pat. Nos. 2,838,192 (Dzvonik); 2,856,087 (Steber); 2,938,642 (Felix); 3,032,353 (Williams et al.); 3,167,198 (Echler et al.); 3,822,899 (Slack); 3,989,266 (Foster) and 4,232,990 (Pierce).
It also is known to employ movable carriages on a wheeled frame or chassis of a trailer for the purpose of launching a boat from the trailer. Representative patents disclosing this type of arrangement are U.S. Pat. Nos. 3,009,589 (Martz)--carriage member 30 provides the launching function; 3,750,805 (Finney)--dolly 9 provides the launching function; and 3,831,790 (Farris)--carriage C provides the launching function.
Although some of the extendable trailers may be reasonably suitable for their intended purpose, particularly those trailers employing a boat supporting cradle movable on a wheeled chassis to provide the launching function, and is believed that the need exists for a simpler arrangement which reliably launches the boat, provides relatively few moving parts, and is capable of operating with only a single winch.